Some types of DoS – Denial of Service – attacks (i.e. smurf, fraggle) utilize IP directed broadcasts in combination with echo protocols and spoofed packets to generate multiplied traffic streams.
This DoS attacks allow the multiplication of traffic through the broadcast mechanism and therefore only require that the sites used to multiply the traffic have enough hosts to increase the factor by which the traffic streams are multiplied.
If the router/gateway at the edge of the LAN forwards the broadcast ping to the LAN, each device on the LAN will respond with an echo-reply (ICMP) or will bounce the traffic (UDP), creating a multiplication of the original traffic flow. The traffic is then directed to the victim. There are usually several bounce sites involved, used to increase the factor by which traffic is multiplied.
A simple mechanism to avoid the propagation of this kind of attack is turning off replies to broadcasts. To do so in your Solaris machine…
ndd -set /dev/ip ip_respond_to_echo_broadcast 0
ndd -set /dev/ip ip_icmp_err_interval 99999
Obviously this should by accompanied by serious planning of your security infrastructure.